Bern
Well-known Member
- Location
- Mount Vernon, WA
I just came back from the local stealership, where I snapped 3 pics from service bulletins related to engine compression testing. First image is from 1965. Note that it gives two options for compression testing: cranking and running. As you can see, they want 420-500 PSI cranking, and go on to say that you should get 555-635 running! WOW! That sounds almost dangerous to me.
The second image is from a bulletin less than a year later, where they advise not to test at running speeds. They retained the 420-510 PSI figure for cranking, same as the service manual.
The third image is from a bulletin from 1980 for the x600 and x700 series tractors. As you can see, compression pressures dropped noticeably for engines that are essentially identical to the pre '75 engines. The "350 +/- 50 PSI" numbers are what I have consistently obtained over the year checking compression on various Basildon Fords. I have never seen any over 400.
To add one more thing: I have a booklet put out by Ford tractor in 1987 titled "Diesel Engine Diagnosis". Under engine compression, it states "290 PSI minimum on all 3,4, & 6 cylinder non-turbo tractors, and 275 minimum on tractors with turbos". It does not give a "normal spec" in that manual.
Clear as mud?
The second image is from a bulletin less than a year later, where they advise not to test at running speeds. They retained the 420-510 PSI figure for cranking, same as the service manual.
The third image is from a bulletin from 1980 for the x600 and x700 series tractors. As you can see, compression pressures dropped noticeably for engines that are essentially identical to the pre '75 engines. The "350 +/- 50 PSI" numbers are what I have consistently obtained over the year checking compression on various Basildon Fords. I have never seen any over 400.
To add one more thing: I have a booklet put out by Ford tractor in 1987 titled "Diesel Engine Diagnosis". Under engine compression, it states "290 PSI minimum on all 3,4, & 6 cylinder non-turbo tractors, and 275 minimum on tractors with turbos". It does not give a "normal spec" in that manual.
Clear as mud?